NEC DPro2070SB Service Manual page 97

CONTINUE 1 CONTINUE 2
Check the output waveform of pre-AMP.
OK
Check the R, G, B video outputs.
NG
Check the 215V line.
OK
OK
Check the voltage of C210R/G/B on the VIDEO PWB.
OK
Expected failure point
L200R/G/B or L201R/G/B
Check the HV operation.
NG
OK
Check the heater voltage.
NG
1) CN211
OK
2) The switching power circuit (See Item 3.4.1)
Check the screen control of FBT.
NG (too low)
OK
NG
Measure the voltage waveform at R200R/G/B on the CRT PWB,
and confirm whether BLACK LEVEL voltage is maintained at
approx. 60-90V.
Measure the voltage between GND and + electrode of C260.
NG
CN211 or 215V line of power circuit
NG
OK
Confirm whether the HV is 27±0.5KV.
Expected failure point
The HV circuit (See Item 3.4.4)
Measure the voltage at both terminals of C203H on the CRT PWB.
Usually, the voltage is approx. 6.3V.
Expected failure point
Confirm the voltage of R205S on the CRT PWB is approx. 600-800V.
T701 on the MAIN PWB or CRT socket on the CRT PWB
Expected failure point
CRT
Measure the waveform at R/G/B output Pins 25, 27
and 29 of IC211 on the VIDEO PWB.
Expected failure point
IC211 on the VIDEO PWB
Expected failure point
L211R/G/B or R211R/G/B
Expected failure point
Confirm the voltage at the base of R250R/G/B is approx. 6V.
NG
R261, D264, R260 or peripheral circuits
Expected failure point
Q250R/G/B or Q251R/G/B
Expected failure point
3-23
Confirm the voltage is approx. 60-100V.
Expected failure point
BLACK LEVEL